Foundation footing question?

Question

I know that a footing is underneath the foundation wall. But is the footing underneath the foundation wall throughout the perimeter of the whole house. Or are footings placed at certain parts of the foundation. If so what would be a typical area of a footing? thanks

Answer 1

I don't really get the distinction that you put on a foundation and a footing. To me the footing and  the foundation mean the same thing.

The width of this depends on the load imposed on it and the allowable bearing pressure of the soil. Since you may not  have an actual test data on the bearing capacity of the soil for the entire length of the wall, then it would be safe to assume that the bearing capacity is not uniform all throughout so that you just have to provide a foundation or footing for the entire length of the wall.

Again, if you don't have the results of a soil bearing test, then you would just have to take the approximate bearing capacity of the type of soil material in your construction site from those shown in books, give a generous factor of safety, (maybe we can term this as factor of ignorance on what it really is), then calculate the width of your footing from there.

You have to consider also that if it becomes quite wide in your calculations, then you may have to reinforce it transversely and increase its thickness to carry the bending load resulting from the footing cantilever.

Answer 2

Footing is another type of foundation, it could be isolated footing, or strip type or slab on grade, usually the foundation or footing are tied up together by a tie beam which runs at the perimeter of the building and inside too,

The size of any footing or foundation depends on the soil bearing capacity and the loads imposed on them as transferred from the above floors and the columns

Answer 3

Two footing types:

1. spread footing which consists of strips or pads of concrete (or other materials) which extend below the frost line and transfer the weight from walls and columns to the soil or bedrock.

2. Another common type is the slab-on-grade foundation where the weight of the building is transferred to the soil through a concrete slab placed at the surface.